Certain electrical components are of a kind which are to carry out an operating movement of a limited extent but for a very short period of time. This makes demands on a drive means which may be rapidly activated, accelerated and decelerated during the short time during which the operating movement is to be carried out. One typical example of such a component is a switch, especially for high and medium voltage. The operation of such a switch is conventionally performed using a mechanical spring as drive source. When breaking is required, the mechanical energy stored in the spring is released, thus obtaining rapid breaking. However, the use of spring means for operating the switch entails certain disadvantages. In the light of these facts, alternative solutions have been arrived at, wherein a rotating electric motor is used for the operation of the switch. Examples of this are described in WO 00/36621 and WO01/71741.
In the switch according to WO00/36621, driving current for the motor is obtained from a source of energy via a control unit. In the switch according to WO01/71741, a converter is used, via which the motor is connected to a source of energy such as, for example, a capacitor bank.
Another example of an electrical component where a limited angular motion in a short time is required is the type of commutating electric switching device disclosed in WO02/056326. Here, the electric switching device comprises a number of movable contact members which are to be rotated rapidly and simultaneously through 90°. For the operation of this movement, an electric motor is described as one embodiment.
The equipment described in the known examples for achieving a rapid and limited operating movement of the motor is relatively costly. Therefore, there is a need to improve the devices according to the prior art.
In the light of the above, the object of the present invention is to provide a rotating electric motor of the kind in question, in which a rapid and limited movement of the motor is provided in a simple, inexpensive and reliable manner.